VIM-439: Implement :sort command.

- Supports "n", "i" and "!" arguments.
Don't override completion and live templates actions

This requires reconfiguring the Vim keymap.
Renamed KeyParser.registerAction() to KeyParser.registerIdeaAction()
Don't reset visual mode after some IntelliJ actions that operate on selections

These actions are: comment by block/line comment, surround with /
surround with template, move statement up/down.

The reason is simplification of action handling as a step towards
keymap-less IdeaVim configuration.
Removed practically unused ActionGroup and AbstractActionGroup interfaces
Removed unused classes
Inlined ResetModeHandler
Flattened com.intellij.idea.vim.handler.* package
Removed unused MakeTags CLI utility
Moved some actions to com.maddyhome.vim.action package
No abstract classes for no reason
Renamed AbstractEditorActionHandler to EditorActionHandlerBase
Some overrides and deprecations
Reformat
Reordered methods
Moved Vim operation groups accessors to VimPlugin

VimPlugin now acts as a facade to Vim operations.
Replaced mapping int codes with Mapping enum
Removed unused actionId field
Removed unused class
Renamed Mapping to MappingMode